Two boxes are connected by a string. The first box has a mass of 4.2 kg and the second 2.8 kg. A string attached to the first box pulls horizontally with a force of
7.5 N. Calculate the tension in the second string if the force of friction on the first
box is 2.0 N and the force of friction on the second is 1.6 N.

The 10-kg double wheel with radius of gyration of 125mm about o is connected to the spring of stiffness k = 600 n/m by a cord which is wrapped securely around the inner hub. if the wheel is released from rest on the incline with the spring stretched 225 mm, calculate the maximum velocity v of its center o during the ensuing motion. the wheel rolls without slipping

Hydrogen atoms are excited by a laser to the =4n=4 state and then allowed to emit. what is the maximum number of distinct emission spectral lines (lines of different wavelengths) that can be observed from this system? 8 6 2 7 4 5 1 3 calculate the wavelength of the 4⟶14⟶1 transition. =λ=

How does the strength of the electrostatic force between an electron and a proton compare to the strength of the gravitational force between them?